Conventional structure of curtain guiding block is primarily to control the left and right movements of the curtain and the structure thereof generally is described in following Taiwanese patents: (1) TW 372436 (filing date: Aug. 6, 1998; titled: Curtain moving system) and (2) TW 355991 (filing date: Aug. 27, 1998; titled: Structure for guiding block of curtain). In these two Taiwanese patents, a right protruding portion of a right wheel base has a vertical slot and the right protruding portion is squeezed into a left protruding portion of the left wheel base. Since the block structure is very small and a hook-shaped structure has to be large enough to be effective, the vertical slot is less effective because the hook-shaped structure is too large and the right protruding portion of the right wheel base is difficult to be squeezed into the left protruding portion of the left wheel base.
Furthermore, in TW 253159 (filing date: Nov. 28, 1994), a right wheel base is inserted into a circular slot of a substrate and restricted by a protruding edge of the circular slot, and a plurality of rolling balls and a left wheel base are orderly disposed thereon. Finally, a protruding circle of the circular slot is heated and compressed to enclose and restrict the left wheel base. This process is inconvenient and costly because the user has to incorporate and purchase an additional heat/compress machine. Therefore, there remains a need for a new and improved guiding block structure to overcome the problems stated above.